test(validators): cover fable accept + unknown-model reject in both gate layers

tests/fixtures/brief-effort-fable.md

@@ -0,0 +1,45 @@
+---
+type: trekbrief
+brief_version: "2.1"
+created: 2026-07-02
+task: "Fixture: high-effort all phases on fable (v5.9 allowlist test)"
+slug: brief-effort-fable
+project_dir: .claude/projects/2026-07-02-brief-effort-fable/
+research_topics: 0
+research_status: complete
+auto_research: false
+interview_turns: 4
+source: fixture
+phase_signals:
+  - phase: research
+    effort: high
+    model: fable
+  - phase: plan
+    effort: high
+    model: fable
+  - phase: execute
+    effort: high
+    model: fable
+  - phase: review
+    effort: high
+    model: fable
+---
+
+# Task: High-effort fable fixture
+
+## Intent
+
+Test fixture for the v5.9 fable model tier — all 4 phases at the
+high effort tier with explicit fable model overrides. Mirrors
+brief-effort-high.md with `model: opus` replaced by `model: fable`.
+
+## Goal
+
+Resolver returns `{effort: 'high', model: 'fable'}` for each of the 4
+PHASE_SIGNAL_PHASES.
+
+## Success Criteria
+
+- Validator passes with no BRIEF_INVALID_MODEL.
+- resolvePhaseSignal(fm, phase).effort === 'high' for all 4 phases.
+- resolvePhaseSignal(fm, phase).model === 'fable' for all 4 phases.

tests/lib/phase-signal-resolver.test.mjs

@@ -50,7 +50,7 @@ test('resolvePhaseSignal — defensive: null/non-object input returns null', ()
 
 test('resolvePhaseSignal — drops model not in BASE_ALLOWED_MODELS (defense-in-depth gate)', () => {
   // MAJOR fix (S4): line that copies `model` must gate against the same
-  // allowlist brief-validator uses (BASE_ALLOWED_MODELS = ['sonnet','opus']),
+  // allowlist brief-validator uses (BASE_ALLOWED_MODELS = ['sonnet','opus','fable']),
   // mirroring how effort is gated against EFFORT_LEVELS. A brief that slipped
   // validation (hand-edited, validation skipped) must not hand a junk model
   // string to a command that then spawns an agent with `model: <junk>`.
@@ -70,15 +70,17 @@ test('resolvePhaseSignal — drops model not in BASE_ALLOWED_MODELS (defense-in-
   assert.ok(!('model' in review), 'model key absent for haiku');
 });
 
-test('resolvePhaseSignal — keeps valid models (sonnet, opus) after gating', () => {
+test('resolvePhaseSignal — keeps valid models (sonnet, opus, fable) after gating', () => {
   const fm = {
     phase_signals: [
       { phase: 'research', effort: 'low', model: 'sonnet' },
       { phase: 'execute', effort: 'high', model: 'opus' },
+      { phase: 'review', effort: 'high', model: 'fable' },
     ],
   };
   assert.equal(resolvePhaseSignal(fm, 'research').model, 'sonnet');
   assert.equal(resolvePhaseSignal(fm, 'execute').model, 'opus');
+  assert.equal(resolvePhaseSignal(fm, 'review').model, 'fable');
 });
 
 test('resolvePhaseSignalFromFile + CLI shim — writes JSON to stdout, exit 0', () => {

tests/validators/brief-validator.test.mjs

@@ -1,7 +1,7 @@
 import { test } from 'node:test';
 import { strict as assert } from 'node:assert';
 import { execFileSync } from 'node:child_process';
-import { mkdtempSync, rmSync, writeFileSync } from 'node:fs';
+import { mkdtempSync, readFileSync, rmSync, writeFileSync } from 'node:fs';
 import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import { validateBriefContent } from '../../lib/validators/brief-validator.mjs';
@@ -255,6 +255,25 @@ test('validateBrief — v5.1.1: UNQUOTED brief_version 2.1 WITH phase_signals is
   assert.ok(!r.errors.find(e => e.code === 'BRIEF_V51_MISSING_SIGNALS'));
 });
 
+// --- v5.9 — fable model tier (BASE_ALLOWED_MODELS widened to three values) ---
+
+test('validateBrief — v5.9: fable phase_signals fixture accepted (no BRIEF_INVALID_MODEL)', () => {
+  const t = readFileSync(new URL('../fixtures/brief-effort-fable.md', import.meta.url), 'utf-8');
+  const r = validateBriefContent(t, { strict: true });
+  assert.equal(r.valid, true, JSON.stringify(r.errors));
+  assert.ok(!r.errors.find(e => e.code === 'BRIEF_INVALID_MODEL'));
+});
+
+test('validateBrief — v5.9: unknown model gpt5 in phase_signals rejected with BRIEF_INVALID_MODEL', () => {
+  const t = GOOD_BRIEF
+    .replace('brief_version: "2.0"', 'brief_version: "2.1"')
+    .replace('source: interview\n', `source: interview\n${SIGNALS_BLOCK.replace('model: opus', 'model: gpt5')}`);
+  const r = validateBriefContent(t, { strict: true });
+  assert.equal(r.valid, false);
+  assert.ok(r.errors.find(e => e.code === 'BRIEF_INVALID_MODEL'),
+    `expected BRIEF_INVALID_MODEL for gpt5, got: ${JSON.stringify(r.errors)}`);
+});
+
 // --- v5.5 — framing enforcement + obligatory TL;DR (gated at brief_version ≥ 2.2) ---
 // Operator decision (S6, option A1): framing + TL;DR are hard BLOCKERs for briefs
 // declaring brief_version ≥ 2.2; existing 2.0/2.1 briefs stay valid (forward-compat,